Apparatuses for disposing tubular covering sleeves for electric-cable joints on supporting elements

ABSTRACT

An apparatus for disposing a tubular covering sleeve for electric-cable joints on a supporting element may include a support for the tubular covering sleeve; a pair of expanders; driving means configured to introduce the expanders into respective ends of the tubular covering sleeve and to cause radial expansion of the tubular covering sleeve; and devices for disposing the tubular covering sleeve in a radially expanded condition on the supporting element. The expanders may be configured to be placed in substantially coaxial positions relative to the tubular covering sleeve at the respective ends of the tubular covering sleeve.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a divisional application of U.S. patent applicationSer. No. 12/087,123, entitled “METHOD OF DISPOSING A TUBULAR SLEEVE ON ASUPPORTING ELEMENT AND APPARATUS TO PUT SAID METHOD INTO PRACTICE” andfiled on Jun. 26, 2008, and claims the associated benefit under 35U.S.C. §121. Parent U.S. patent application Ser. No. 12/087,123 was anational stage entry from International Application No.PCT/IT2005/000768, filed on Dec. 28, 2005, in the Receiving Office ofthe Italian Patent and Trademark Office. The entire contents of parentU.S. patent application Ser. No. 12/087,123 and InternationalApplication No. PCT/IT2005/000768 are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a method of disposing a tubular sleeveon a supporting element, as well as to an apparatus for putting saidmethod into practice.

In particular, the present invention pertains to a method and anapparatus for radially expanding a tubular sleeve and disposing it on asupporting element for splicing of at least one pair of electric cables,said sleeve being adapted to restore the electric connection betweencable sections for energy transport or distribution.

The electric cables to be submitted to splicing following the method ofthe present invention can be cables either of the unipolar type(unipolar cables) or of the multipolar type (bipolar or three-polecables, for example). These electric cables can be used for transmissionor distribution of direct current (DC) or alternating current (AC). Theexpanded sleeves according to the method and apparatus of the inventioncan be applied to any electric connection between cables being part ofan electric network, as well as to any electric connection between acable and an electric apparatus, a terminal for example.

STATE OR THE ART

Cables for energy transport and distribution, in particular fortransport or distribution of medium- and high-voltage energy, generallycomprise, starting from a radially innermost position to a radiallyoutermost position of the cable: an electrically conductive conductor(generally of metal material), an inner semiconductive layer, aninsulating layer, an outer semiconductive layer, a metal shield—usuallymade of aluminium, lead or copper—and an outer polymer sheath forprotection from the surrounding atmosphere. The assembly consisting ofthe following constituent elements of the cable in the mentionedsequence: conductor, inner semiconductive layer, insulating layer andouter semiconductive layer, is usually referred to as “cable core”.

In order to splice two electric cables, of the single-pole type forexample, the ends of the latter are previously treated so as to exposethe constituent elements of said cables over a portion of apredetermined length. Subsequently, the two cables are spliced in orderto form an electric connection between the conductors of same, bywelding or clamping of the conductors for example, and then aseparately-produced tubular covering sleeve is positioned at thesplicing region (i.e. the region where the conductors have beenspliced).

The tubular sleeve generally comprises a plurality of elements adaptedto restore the electric and mechanical continuity of the constituentelements of the cables to be submitted to splicing. This tubularcovering sleeve can be applied to the splicing region in the form of ashrinkable tubular sleeve, by previously radially expanding the sleeveitself and subsequently causing shrinkage of same by heating (aheat-shrinkable sleeve) or by removing a previously disposed tubularsupporting element aiming at keeping the tubular sleeve—made ofresilient material—in a radially expanded condition (a cold-shrinkablesleeve).

Positioning of the sleeve on the supporting element is obtained throughdevices adapted to fit the sleeve on said supporting element. Inparticular, these devices cause a radial expansion of the sleeve throughdirect insertion of the supporting element from one end of the sleeve orthrough use of a suitable expanding element into which the supportingelement is subsequently introduced.

Document EP0368236, in the name of the same Applicant, discloses aprocess and an apparatus for inserting a rigid support into a sleeve forsplicing of electric cables. To this aim, the apparatus described inthis document comprises an actuator adapted to engage a rigid tubularsupport and the above mentioned sleeve.

In more detail, the actuator acts on a pulling bar connected to an ogiveintegral with a front end of the rigid tubular support. This pulling bartransmits a force oriented in an axial direction to the tubular support,so that said support is inserted into the sleeve. The actuator is suchoperated that the rigid support dragged along by the pulling barpreviously introduced through the sleeve, is inserted into the sleevestarting from a first end of the sleeve itself and drawn in thedirection of the second end of the latter. The apparatus furthercomprises a counter-unit set to engage the tubular sleeve in order tofix positioning of same in an axial direction. The counter-unitcomprises two shell halves that can be moved close to each other andeach having a plurality of homogeneously distributed presser elements todefine a holding seat within which the sleeve is housed when the shellhalves are close to each other. The presser elements apply a centripetalradial force to the outer surface of the sleeve to make said surfaceadhere to the presser elements so as to generate counter-forcesdistributed over the whole sleeve length that are capable ofcounteracting the thrust action exerted by the tubular support when itis introduced into the sleeve itself.

Document WO 2/07280 discloses a device for disposing a sleeve expandablein a radial direction on an elongated element provided with an outercross section larger than the maximum inner cross section of the sleevein a non-expanded configuration. The device comprises a first and asecond units both having a section expandable in a radial direction andbeing insertable into the sleeve. In addition, the first unit isinsertable into the second. To enable pre-expansion of the sleeve, thedevice further comprises a first and a second rigid tubes that aresequentially introduced into the first unit.

Document WO 02/07281 discloses a device for applying at least tworadially expandable sleeves onto at least two parallel elongatedelements provided with an outer cross section larger than the maximuminner cross section of each of the sleeves in a non expandedconfiguration. The device comprises at least two expandable tubularsections integral with a common base, each of said sections including anenlarged portion and an expandable portion provided with a plurality offlexible tailpieces. The device is inserted into the sleeve and theelongated element is subsequently inserted into said device.

Document U.S. Pat. No. 6,049,960 discloses a method and a device forcausing sliding and positioning of components in the form of aresiliently expandable sleeve in a radial direction, on cylindrical orconical bodies with an outer diameter larger than the inner diameter ofsaid components. The device comprises a collar to which a plurality ofelongated and flexible tabs are connected, said tabs being spaced apartthe same distance and being disposed in coaxial relationship with thecentral axis of the collar. The free ends of the tabs are first insertedinto the sleeve-shaped component and then the sleeve is mounted togetherwith the device itself over the end of the previously prepared cable,with the tabs disposed between the sleeve-shaped component and the endof the cable constituting the base body.

SUMMARY OF THE INVENTION

The Applicant has perceived the necessity to improve the known processesfor installation of tubular sleeves that are used at the splicing regionbetween at least one pair of electric cables.

In particular, the Applicant has sensed the necessity to improve theradial-expansion methodology for the above sleeves as it has found thatthe known art solutions cause arising of opposite forces of differentamount on the (axially opposite) end portions of the sleeve itself.

Actually, the Applicant has become aware of the fact that an asymmetricdistribution of the elastic forces acting on distinct portions of thesleeve (a non-symmetric distribution of efforts and deformationsrelative to a middle plane of the sleeve perpendicular to thelongitudinal axis thereof) is due to the fact that the known artsolutions involve insertion of the expansion devices starting from oneend alone of the sleeve.

In fact, the Applicant could ascertain that introduction of an expansiondevice starting from a single end of the sleeve causes generation ofaxial-compression forces in the sleeve portion concerned with entry ofthe expansion device and of axial pulling forces in the sleeve portionconcerned with exit of the expansion device, said exit portion beingaxially opposite to said entry portion.

The Applicant has verified that an asymmetric distribution of theefforts causes arising of asymmetric deformations (in particular plasticsets) that keep frozen within the sleeve material and therefore canimpair a correct operation of the sleeve itself once the latter has beenpositioned on the splicing region. Due to said asymmetric deformations,the sleeve expanded according to the known art methodologies andapparatus can in fact have different radial sizes along its axialextension, which will result in an asymmetric and uneven tighteningaction of the sleeve on the splicing region.

The Applicant has also found that, should the sleeve to be submitted toexpansion be provided with an outer sheath, the latter being generallycoupled with the sleeve by interposition of a lubricating agent utilisedto promote laying of the outer sheath on said sleeve, and if theexpansion devices are introduced from one end alone of the sleeveitself, the outer sheath can suffer a modification in its axial centringrelative to the underlying sleeve. In other words, the Applicant hasfound that, should the expansion devices be inserted from a singlesleeve end, in order to avoid axial displacement of the outer sheathrelative to the sleeve it is necessary to position the sheath on thesleeve at a position that is out-of-centre by an amount equal to theaxial sliding to which the sheath is submitted during introduction ofthe expansion devices into the sleeve, so that the result, whenexpansion has been completed, be a correct centring of the outer sheathon the underlying sleeve.

The Applicant therefore has become aware of the necessity to obtaintubular sleeves radially expanded in a symmetric manner relative to amiddle plane perpendicular to the longitudinal axis of the sleevesthemselves, so that possible permanent sets generated on the sleevefollowing introduction of the expansion devices be symmetricallydistributed along the longitudinal extension of the sleeve and, as aresult, an even tightening action of the sleeve on the splicing regionbe ensured, as well as centring of the outer sheath on the sleeve,should the latter be already provided with said sheath.

The Applicant has found that the method of radially expanding a tubularsleeve is advantageously greatly improved if the expansion is carriedout in a gradual and symmetric manner starting from both axiallyopposite ends of the sleeve to be submitted to expansion. The Applicantin fact has verified that in this way the axially opposite portions ofthe sleeve are submitted to the same distribution of efforts. Therefore,in a first aspect, the present invention relates to a method ofdisposing a tubular covering sleeve for electric-cable joints on asupporting element, said method comprising the steps of: arranging atubular sleeve; causing radial expansion of said tubular sleeve startingfrom axially opposite end portions of said tubular sleeve; arrangingsaid tubular sleeve in a radially-expanded condition on a supportingelement.

Preferably, radial expansion of the tubular sleeve is carried outgradually starting from the end portions of said sleeve towards anaxially intermediate portion thereof.

More preferably, radial expansion of the tubular sleeve is carried outsimultaneously on both the end portions of the tubular sleeve.Preferably, radial expansion of the tubular sleeve is radiallysymmetric.

In a further aspect, the present invention relates to an apparatus fordisposing a tubular covering sleeve for electric-cable joints on asupporting element, said apparatus comprising: a support for a tubularsleeve; a pair of expanders to be placed to a substantially coaxialposition relative to said tubular sleeve, each at a respective end ofthe sleeve; driving means adapted to introduce the expanders into therespective ends of the sleeve and to cause radial expansion of thesleeve itself; devices for disposing the sleeve in a radially expandedcondition on said supporting element.

Further features and advantages will become more apparent from thedetailed description of some preferred, but not exclusive embodiments ofa method of disposing a tubular covering sleeve for electric-cablejoints on a supporting element, as well as of an apparatus for disposinga tubular covering sleeve for electric-cable joints on a supportingelement, in accordance with the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

This description will be set out hereinafter with reference to theaccompanying drawings, given by way of non-limiting example, in which:

FIG. 1 is a partly sectioned side view of an apparatus for arranging atubular covering sleeve for electric-cable joints on a supportingelement in accordance with the present invention, in a first operatingconfiguration;

FIG. 2 shows an enlarged portion of the apparatus in FIG. 1 in the firstoperating configuration;

FIG. 2 a shows a detail to an enlarged scale of the portion in FIG. 2;

FIG. 3 shows the apparatus in FIG. 1 in a second operatingconfiguration;

FIG. 3 a shows a detail to an enlarged scale of the apparatus in FIG. 3;

FIG. 4 shows the apparatus seen in FIG. 1 in a third operatingconfiguration corresponding to a first step of radial expansion of thesleeve;

FIG. 5 is a partial longitudinal section of the sleeve during the firststep of radial expansion shown in FIG. 4;

FIGS. 6 to 8 show respective subsequent steps of radial expansion of thesleeve;

FIG. 9 shows the enlarged portion seen in FIG. 2 in the configurationtaken in the operating steps of FIGS. 7 and 8;

FIG. 10 shows the apparatus seen in FIG. 1 in a further operatingconfiguration;

FIG. 11 shows the sleeve installed on the supporting element.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to the drawings, an apparatus for disposing a tubularcovering sleeve 2 for electric-cable joints on a supporting element 3 inaccordance with the present invention has been generally identified byreference numeral 1.

Apparatus 1 comprises a support 4 capable of supporting and locking thesleeve 2 during a step of radial expansion of the latter. In theembodiment shown in the accompanying drawings, this support 4 has a pairof plates 5 parallel to each other and mutually spaced apart bysubstantially the same distance as the length of sleeve 2. Each plate isprovided with a shaped opening 6 adapted to receive one end 7 of saidsleeve 2. To this aim, each of the ends 7 of sleeve 2 has an outerdiameter smaller than the outer diameter of an axially intermediateportion 8 thereof, so as to form a shoulder 9 adapted to abut againstthe edges of a respective opening 6. Preferably, opening 6 of the platesconforms in shape to the respective end 7 of the sleeve and can modifyits radial size so as to become wide during expansion of the ends 7 ofsleeve 2 and follow deformation of the latter.

Apparatus 1 further comprises a pair of expanders 10 each moved bydriving means 11 capable of disposing the expanders to a positionsubstantially coaxial with the sleeve 2 put on the support 4 and closeto a respective end 7 of the sleeve 2 itself. The driving means 11further carries out introduction of the expanders 10 into the respectiveends 7 of sleeve 2, so as to cause radial expansion of the latter. Theexpanders 10 are preferably introduced as far as their distal ends 10 aabut against each other at the axially intermediate portion 8 of sleeve2.

Preferably but not exclusively, the two expanders 10 are of thetelescopic type and have the same structure. Advantageously, theexpanders 10 are preferably introduced into sleeve 2 by a synchronisedand symmetric movement relative to a symmetry plane “P” transverse to alongitudinal axis “X” of the sleeve 2 and passing through the axiallyintermediate portion 8 of the latter, so as to cause a radial expansionwhich too is symmetric relative to said plane “P”.

In the preferred embodiment herein shown, each of the expanders 10comprises a radially external tubular body 12 of circular section andprovided with a side surface 13 susceptible of engagement with an innerwall 14 of sleeve 2. A proximal end 15 a of the radially externaltubular body 12 is provided with a flange 16 having a tailpiece 17extending radially away from body 12 and carrying a lead nut 18installed on a first worm screw 19. Distal ends 15 b of the radiallyexternal tubular bodies 12 face each other and are provided with abevelled edge in the form of a truncated cone, better seen in FIGS. 5-8,to promote introduction into sleeve 2.

The first worm screw 19 extends parallel to the longitudinal axis “X” ofsleeve 2 and has two portions 19 a, 19 b with contrary threads, eachsupporting one of the lead nuts 18 connected to a respective radiallyexternal tubular body 12. Said two portions 19 a, 19 b extendsymmetrically starting from the symmetry plane “P” and are supported bya suitable fixed frame, not shown.

The driving means 11 comprises a first main motor 20, an electric motorfor example, operatively in engagement with the first worm screw 19,through either a belt drive 21 for example, or a chain or gear drive. Inthe non-limiting example shown, a belt 22 is wrapped on a driving pulley23 integral with the shaft 24 of the first main motor 20 and on a drivenpulley 25 integral with the first worm screw 19. Rotation of the firstworm screw 19 in a first direction causes translation of the tworadially external tubular bodies 12 close to each other, towards thesymmetry plane “P”, while rotation in the opposite direction causesmutual spacing apart of same.

Each expander 10 further comprises a radially internal body 26 movablebetween a disengaged position (FIGS. 1 and 10) at which it lies spacedapart from the respective radially external tubular body 12, preferablyat a position axially offset relative to said radially external body 12,and an engaged position (FIG. 3), at which it is inserted in therespective radially external tubular body 12. The first main motor 20connected to the radially external tubular bodies 12 is adapted tosimultaneously introduce the expanders 10 into sleeve 2 while theradially internal body 26 is in the engaged position.

To this aim, each radially internal body 26 is mounted on a respectivemain support assembly 27 which in turn is installed on an auxiliarysupport assembly 28. Both the mentioned assemblies 27, 28 arediagrammatically shown in the figures as rectangular tables. Each of themain support assemblies 27 and each of the auxiliary support assemblies28 is moved along a direction parallel to the longitudinal axis “X” ofsleeve 2 by a respective second worm screw 29 extending parallel to saidlongitudinal axis “X” and is supported by a suitable fixed frame, notshown. The second worm screw 29 bears a lead nut, not shown, connectedto the respective main support assembly 27 through the auxiliary supportassembly 28. In more detail, the mentioned lead nut is integral with theauxiliary support assembly 28 and in the accompanying drawings is notshown as it is concealed behind it. A second main motor 31 being part ofthe driving means 11, is operatively engaged with the second worm screw29 to move the respective radially internal body 26 together with themain 27 and auxiliary 28 support assemblies on parallel guides 30extending along a direction parallel to the longitudinal axis “X”. Thesecond main motor 31 also of the electric type for example, is connectedto said second worm screw 29 through either a belt drive 32 for example,or a chain or gear drive. Preferably, as shown, a belt 22 is wrapped ona driving pulley 23 integral with the shaft 24 of the second main motor31 and on a driven pulley 25 integral with the second worm screw 29.Rotation of the second screw 29 in a first direction causes translationof the respective radially internal tubular body 26 close to thesymmetry plane “P”, while rotation in the opposite direction causesmoving apart of same. Preferably, the second main motors 31 are operatedby a single control unit, not shown, for simultaneous and symmetricmovement of the radially internal tubular bodies 26.

Further mounted on the auxiliary support assembly 28 is a third wormscrew 33 extending along a direction transverse to the longitudinal axis“X” of sleeve 2 and to the second worm screw 29 and supporting aconcealed lead nut integral with the respective main support assembly27. The auxiliary support assembly 28 therefore is maintained to aninterposed position between the second worm screw 29 and the respectivemain support assembly 27,

A third main motor 35 is located over the auxiliary support assembly 28and is connected to the respective third worm screw 33, to move the mainsupport assembly 27 along mutually parallel guides 34 transverse to thelongitudinal axis “X” of sleeve 2 and positioned on the auxiliarysupport assembly 28. In a manner quite similar to the first 20 andsecond 31 main motors, the third main motor 35 is connected to the thirdworm screw 33 by means either of a belt drive 36 for example, or of achain or gear drive. Preferably, as shown, a belt 22 passes over adriving pulley 23 integral with the shaft 24 of the third main motor 35and over a driven pulley 25 integral with the third worm screw 33.Rotation of the third screw 33 in a first direction causes translationof the main support assembly 27 and the respective radially internaltubular body 26 close to the longitudinal axis “X” of sleeve 2, whilerotation in the opposite direction causes moving apart of same.

The radially internal body 26, in a first operating configuration shownin FIG. 2, has a tapered distal end 37, in the form of an ogive forexample, to facilitate introduction of the body itself into sleeve 2 andcause gradual expansion of ends 7.

In more detail (FIGS. 2 and 2 a) in the preferred embodiment hereinshown, each of the radially internal bodies 26 comprises a centralelement 38 which has a distal portion 39 provided with a tapered distalend 39 a in the form of an ogive for example, that in the firstoperating configuration in FIGS. 2, 2 a and 10, constitutes the point ofthe ogive 37 of the radially internal body 26 considered as a whole. Thedistal portion 39 carrying the ogive comprises a cylindrical length 41having an annular ridge 42 at the rear, i.e. towards the proximal end 40of the central element 38. The central element 38 further has anintermediate length 43 interposed between the proximal end 40 and theannular ridge 42, which intermediate length 43 is rod-shaped andterminates with an outer thread 44 placed on said proximal end 40. Thecylindrical length 41 is further provided with radial seats 45 forhousing keys 46 set to prevent mutual rotation between the differentelements of the radially internal body 26, as better detailed in thefollowing of the present specification.

The radially internal body 26 further comprises an outer tubular element47 disposed around the central element 38 and slidably in engagementwith said central element 38. Preferably, an intermediate tubularelement is located between the central element 38 and the outer tubularelement 47 and is slidably in engagement with both of them. While in theembodiment shown only one intermediate element 48 is represented, alsoadoption of a plurality of intermediate elements 48 coaxial with eachother falls within the scope of the present invention, so as to define amulti-stage telescopic radially internal body 26. Preferably, saidstages are four in number.

The outer tubular element 47 has a distal portion 49 provided with atapered distal end 49 a, preferably of frusto-conical shape. In detail,the distal portion 49 internally has axial splines 50 adapted toslidably house the keys 46 inserted in the radial seats 45 formed in theintermediate tubular element 48, to prevent mutual rotation of saidintermediate tubular element 48 relative to the outer tubular element47. The wall of the distal portion 49 of the outer tubular element 47has an increased thickness than an intermediate length 51 of said outertubular element 47 and delimits a passageway adapted to receive andguide a distal portion 52 of the intermediate tubular element 48. Aproximal end 53 of the outer tubular element 47 has an outer thread 54on which a lead nut 55 is installed, said lead nut 55 being rotatablymounted, by means of bearings 56 for example, in a seat 57 formed in ahousing body 58 set up in an integral manner on the main supportassembly 27 (FIGS. 2, 3 a and 9). The lead nut 55 mounted on the outertubular element 47 is axially locked relative to said housing body 58.

Also the distal portion 52 of the intermediate tubular element 48 has adistal end 52 a provided with a bevel adapted to give it a frustoconicaltapered shape and is internally provided with axial splines 59 intowhich the keys 46 housed in the radial seats 45 of the cylindricallength 41 of the central element 38 are slidably engaged, to preventmutual rotation between said intermediate tubular element 48 and thecentral element 38. The distal portion 52 further comprises acylindrical length 60 having an annular ridge 62 at the rear, i.e.towards a proximal end 61 of the intermediate tubular element 48, whichannular ridge 62 is similar to the annular ridge 42 of the centralelement 38.

The proximal end 61 of the intermediate tubular element 48 has an outerthread 63 on which a lead nut 64 is mounted which is rotatably engaged,by means of bearings 56 for example, into the proximal end 53 of theouter tubular element 47. The lead nut 64 mounted on the intermediatetubular element 48 is axially locked relative to said outer tubularelement 47 and is movable therewith.

Finally, a further lead nut 65 is mounted on the thread 44 of thecentral element 38, is rotatably engaged by means of bearings 56 forexample, into the proximal end of the intermediate tubular element 48,and is axially locked relative to said intermediate tubular element 48and movable therewith.

In the instance not shown in which several intermediate tubular elementsare present, the structure of each of them is substantially identicalwith that described for the intermediate tubular element 48 depicted inthe figures.

In a further alternative embodiment not shown, the intermediate tubularelement 48 is absent and the lead nut 65 of the central element 38 isdirectly mounted to the proximal end 53 of the outer tubular element 47.

The central element 38, intermediate tubular element 48 and outertubular element 47 are mutually movable between said first operatingconfiguration, at which the ogive-shaped end 39 a and the tapered distalends 49 a, 52 a form a continuous tapered and preferably substantiallyconical surface shown in FIGS. 2 and 2 a, and a second operatingconfiguration at which the point of the ogive-shaped end 39 a and theedges 66 of the tapered distal ends 49 a, 52 a lie in the same plane(FIG. 9). In the first operating configuration in FIG. 2 a, theshoulders defined by the annular ridges 42, 62 of the central element 38and the intermediate tubular element 48 lie against shoulders 67 locatedon inner surfaces of the intermediate tubular element 48 and the outertubular element 47, respectively.

The driving means 11 further comprises a pair of auxiliary motors 68each of which is fixedly mounted on the main support assembly 27 and isconnected to the respective outer tubular element 47 by means of a beltdrive 69 for example, or of a chain or gear drive. In the embodimentshown a belt 22 is wrapped on a driving pulley 23 fitted on shaft 24 ofthe first auxiliary motor 68 and on the lead nut 55 of the outer tubularelement 47. Rotation of the lead nut 55 caused by the first auxiliarymotor 68 through belt 22 causes translation of the outer tubular element47 relative to the main support assembly 27 on which it is installed.

A second pair of auxiliary motors 70 moves the intermediate tubularelements 48. In particular, each of the second auxiliary motors 70 isinstalled on the main support assembly 27 and connected to therespective intermediate tubular element 48 by means of either a beltdrive 71, or a chain or gear drive. In the embodiment shown, a belt 22is wrapped on a driving pulley 23 fitted on the shaft 24 of the secondauxiliary motor 70 and on the lead nut 64 of the intermediate tubularelement 48. Rotation of the lead nut 64 caused by the second auxiliarymotor 70 through belt 22 causes translation of the intermediate tubularelement 48 relative to the outer tubular element 47. The secondauxiliary motor 70 is moved on guides 72 substantially parallel to thelongitudinal axis “X” of sleeve 2 and placed on the first main supportassembly 27, to follow the axial movement of the outer tubular element47. Axial-motion transmission from the outer tubular element 47 to thesecond auxiliary motor 70 preferably takes place through a rigidconnection, not shown.

A third pair of auxiliary motors 73 moves the central elements 38. Inparticular, each of the third auxiliary motors 73 is installed on themain support assembly 27 and is connected to the respective centralelement 38 by means either of a belt drive 74 for example, or of a chainor gear drive.

As for the first 68 and second 70 auxiliary motors, a belt 22 is wrappedon a driving pulley 23 fitted on the main shaft 24 of the thirdauxiliary motor 73 and on the lead nut 65 of the central element 38.Rotation of the lead nut 65 caused by the third auxiliary motor 73through belt 22 causes translation of the central element 38 relative tothe intermediate tubular element 48. The third auxiliary motor 73 ismoved on guides 75 that are substantially parallel to the longitudinalaxis “X” of sleeve 2 and placed on the first main support assembly 27,to follow axial motion of the intermediate tubular element 48.Axial-motion transmission from the intermediate tubular element 48 tothe third auxiliary motor 73 preferably takes place by a rigidconnection, not shown.

Each of the main support assemblies 27 comprises a locking device 76capable of making the radially external tubular body 12 of the expander10 and the main support assembly 27 integral with each other.

In detail, the locking device 76 is defined by a tailpiece 77 of thehousing body 58 on which a hydraulic or pneumatic cylinder 78 is mounted(FIG. 3 a). The rod 79 of the cylinder 78 is slidable in a hole 80formed in the tailpiece 77 along a radial direction.

The radially external tubular body 12 has a housing 81 located on theproximal end 15 a and formed in the flange 16, for example. Housing 81is capable of receiving the rod 79 when the radially internal body 26 isin the above mentioned engaged position, at which it is inserted in therespective radially external tubular body 12. The rod 79 is thereforemovable between a backward position, at which it is completely containedin hole 80 and an extracted position at which it projects from said hole80 to enter housing 81.

In use, the sleeve 2 in a rest configuration, i.e. not yet expanded, ispositioned on the support 4 and has its ends 7 placed in the openings 6.As shown in FIG. 1, the radially external tubular bodies 12 of theexpanders 10 are in alignment with the longitudinal axis “X”, theirdistal ends 15 b facing the ends 7 of sleeve 2. In addition, theradially internal bodies 26 too lie in alignment with the longitudinalaxis “X”, their distal ends 37 facing the proximal ends 15 a of theradially external tubular bodies 12. Each of the radially internaltubular bodies 26 is in the first operating configuration, better shownin FIGS. 2 and 2 a, in which the ogive-shaped end 39 a and the tapereddistal ends 49 a, 52 a form a continuous and substantially conicalsurface.

Subsequently, by operating the second main motors 31, the radiallyinternal bodies 26, together with the respective main 27 and auxiliary28 support assemblies, are moved forward along the respective secondworm screws 29, until each radially internal body 26 is completelyinserted into the corresponding radially external tubular body 12, andhousing 81 is disposed close to hole 80 of the tailpiece 77 (FIGS. 3 and3 a). The rod 79 of the cylinder 78 is inserted in hole 80 to lock eachradially external tubular body 12 on the respective main supportassembly 27.

At this point, the first main motor 20 drives in rotation the first wormscrew 19 that, through the lead nuts 18 connected therewith, drags alongthe two expanders 10, each integral with its main 27 and auxiliary 28support assemblies, and moves them close to the symmetry plane “P”.During this step, the auxiliary assemblies 28 are preferablydisconnected from the second worm screw 29 and move on their guidesbeing dragged along by the first worm screw 19 alone. During movingforward towards said symmetry plane “P”, the distal ends 10 a of theexpanders 10, formed by the distal ends 15 b, 37 of the radiallyexternal tubular body 12 and the radially internal body 26, enter theends 7 of sleeve 2 causing radial expansion of said ends until thedistal ends 10 a, i.e. the ogive points, abut against each other at thesymmetry plane “P (FIGS. 4 and 5). Under this condition, visible in FIG.5, the end portions 7 a of sleeve 2 are already expanded while theaxially intermediate portion 8 is only partly expanded.

To complete expansion, the first 68, second 70 and third 73 auxiliarymotors move the tubular elements 47, 48 and the central element 38 in adirection opposite to the moving forward direction of the respectiveradially external tubular body 12, so as to first bring the distal ends39 a of the central elements 38 into mutual contact, then the distalends 49 a, 52 a of the tubular elements 47, 48 and finally the distalends 15 b of the radially external tubular bodies 12.

In more detail, after the ogive points 10 a have come into mutualcontact (FIG. 5), the main 27 and auxiliary 28 assemblies, upon theaction of the first main motors 20, go on moving forward towards thesymmetry plane “P” taking along with them the radially external tubularbody 12, outer tubular element 47 and intermediate tubular element 48that are integral with each other.

The third auxiliary motor 73 of each of the two expanders 10 acts on thecentral element 38 making it move backwards relative to the intermediatetubular element 48, so as to maintain its distal end 39 a fixed on thesymmetry plane “P”. The radially external tubular body 12, outer tubularelement 47 and intermediate tubular element 48 start gradual expansionalso of the axially intermediate portion 8 of sleeve 2.

When the distal ends 52 a of the intermediate tubular element 48 comeinto mutual contact (FIG. 6), intervention of the second auxiliary motor70 working together with the third auxiliary motor 73 occurs to causejoint backwards movement of the central element 38 and the intermediatetubular element 48 relative to the outer tubular element 47, so as toalso keep the distal ends 52 a of the intermediate tubular element 48fixed on the symmetry plane “P”, while the outer tubular elements 47together with the radially external tubular bodies 12 go on movingforward.

When the distal ends 49 a too of the outer tubular element 47 come intomutual contact (FIG. 7), intervention of the first auxiliary motor 68working together with the second 70 and third 73 auxiliary motorsoccurs, to cause joint moving backwards of the central element 38, theintermediate tubular element 48 and the outer tubular element 47relative to the radially external tubular body 12. Said radiallyexternal tubular bodies 12 go on moving forward upon the action of thefirst main motor 20, until bringing their distal ends 15 b into mutualcontacts and completing radial expansion of sleeve 2 (FIG. 8).

Where a plurality of intermediate tubular elements 48 is present, theradially internal body 26 is formed with a plurality of telescopictubular elements disposed around the central element 38. Thesetelescopic tubular elements are moved forward in succession from theinnermost one to the outermost one until abutment of the respectivetapered distal ends, one after the other.

In order to obtain full expansion of sleeve 2, abutment of the tworadially external bodies 12 is sufficient. Therefore, according to avariant of the present invention, only the radially external bodies 12abut against each other without bringing the radially internal bodies 26into mutual contact.

When expansion has been completed, the radially internal bodies 26 ofthe expanders 10 are unlatched and pulled out of the radially externaltubular bodies 12. To this aim, the auxiliary assemblies 28 areconnected with the respective second worm screws 29 and axially movedapart from sleeve 2 through the action of the second main motors 31. Inaddition, the radially internal bodies 26, once separated and axiallyspaced apart, are radially shifted relative to the longitudinal axis “X”of the sleeve 2 itself, moving the main support assemblies 27 along therespective guides 34 upon the action of the third main motors 35 andthird worm screws 33 (FIG. 10).

Devices not shown carry out insertion of the supporting element 3 intothe radially external tubular bodies 12 still disposed in the sleeve 2.Finally, said radially external tubular bodies 12 radially interposedbetween the sleeve 2 and supporting element 3 are simultaneously drawnout upon operation of the first motor 20, to enable shrinkage of thesleeve 2 on the supporting element 3 (FIG. 11).

A method of disposing the tubular covering sleeve 2 for electric-cablejoints on the supporting element 3 comprises the steps of causing radialexpansion of the tubular sleeve 2 starting from the axially opposite endportions 7 a of the sleeve 2 itself and disposing the tubular sleeve 2in a radially expanded condition on the supporting element 3.

Irrespective of the apparatus used, in accordance with the presentinvention, this radial expansion is preferably carried out graduallystarting from the end portions 7 a to the axially intermediate portion 8of the tubular sleeve 2 and simultaneously on both of the end portions 7a, so that said radial expansion is radially symmetric relative to theabove described symmetry plane “P”. After the radial expansion step,sleeve 2 preferably has an inner diameter larger than the outer diameterof the supporting element 3 on which it is to be disposed and laying isproduced by causing a radial shrinkage of sleeve 2 on the supportingelement 3 itself.

The supporting element 3 is preferably an independent tubular support,as specified above in describing operation of apparatus 1.

Alternatively, the supporting element consists of the ends themselves ofthe cables to be spliced, the above described operations being conducteddirectly in the trench.

Alternatively, the supporting element is made up of the two radiallyexternal tubular bodies 12. In this case, the two radially externaltubular bodies 12 are disconnected from the flanges 16 integral with thelead nuts 18 mounted on the first worm screw 19 and need replacement byfurther bodies 12 expansion of a subsequent sleeve 2 is to be carriedout.

The above described movements are preferably and advantageouslycontrolled and governed by an electronic programmable control unitconnected to all or part of motors 20, 31, 35, 68, 70, 73 and possiblyto sensors, not shown, adapted to detect the positions, displacementsand velocities of the different parts of the apparatus, for example.

1-18. (canceled)
 19. An apparatus for disposing a tubular covering sleeve for electric-cable joints on a supporting element, the apparatus comprising: a support for the tubular covering sleeve; a pair of expanders: driving means configured to introduce the expanders into respective ends of the tubular covering sleeve and to cause radial expansion of the tubular covering sleeve; and devices for disposing the tubular covering sleeve in a radially expanded condition on the supporting element; wherein the expanders are configured to be placed in substantially coaxial positions relative to the tubular covering sleeve at the respective ends of the tubular covering sleeve.
 20. The apparatus of claim 19, wherein the expanders are structurally identical.
 21. The apparatus of claim 19, wherein the expanders are of a telescopic type.
 22. The apparatus of claim 19, wherein each of the expanders comprises: a radially external tubular body configured to be brought into engagement with an inner wall of the tubular covering sleeve; and a radially internal body that is axially movable relative to the radially external tubular body.
 23. The apparatus of claim 22, wherein the radially internal body is movable between a disengaged position, at which the radially internal body lies spaced apart from a respective radially external tubular body, and an engaged position, at which the radially internal body is inserted in the respective radially external tubular body.
 24. The apparatus of claim 22, wherein the radially internal body has an ogive-shaped distal end.
 25. The apparatus of claim 23, wherein at the disengaged position, the radially internal body is axially offset from the respective radially external tubular body.
 26. The apparatus of claim 23, wherein the driving means comprises: a first main motor connected to the radially external tubular bodies; wherein the first main motor is configured to simultaneously introduce the expanders into the tubular covering sleeve while the radially internal body is at the engaged position.
 27. The apparatus of claim 26, wherein the first main motor is operatively engaged with a first worm screw parallel to a longitudinal axis of the tubular covering sleeve, wherein the first worm screw comprises two portions with contrary threads, and wherein each portion of the first worm screw supports a lead nut connected to a respective radially external tubular body.
 28. The apparatus of claim 27, wherein a belt drive connects the first main motor to the first worm screw.
 29. The apparatus of claim 26, wherein the driving means further comprises: a second main motor for each radially internal body; wherein each second main motor is configured to move the respective radially internal body along a direction parallel to a longitudinal axis of the tubular covering sleeve.
 30. The apparatus of claim 29, wherein each second main motor is operatively engaged with a respective second worm screw parallel to the longitudinal axis of the tubular covering sleeve, and wherein each second worm screw supports a lead nut connected to a respective main support assembly of the respective radially internal body.
 31. The apparatus of claim 30, wherein a belt drive connects each second main motor to the respective second worm screw.
 32. The apparatus of claim 30, further comprising, an auxiliary support assembly interposed between the respective second worm screw and the respective main support assembly; wherein the auxiliary support assembly supports a third main motor connected to the respective main support assembly, and wherein the third main motor is configured to move the respective main support assembly along a direction transverse to the longitudinal axis of the tubular covering sleeve.
 33. The apparatus of claim 32, wherein each third main motor is operatively engaged with a respective third worm screw installed on the auxiliary support assembly perpendicular to the longitudinal axis of the tubular covering sleeve, and wherein each third worm screw supports a lead nut mounted on the respective main support assembly.
 34. The apparatus of claim 33, wherein a belt drive connects each third main motor to the respective third worm screw.
 35. The apparatus of claim 22, wherein the radially internal body comprises: a central element having an ogive-shaped distal end; and an outer tubular element disposed around the central element; wherein the outer tubular element has a tapered distal end axially movable relative to the central element.
 36. The apparatus of claim 35, wherein the radially internal body further comprises: at least one intermediate tubular element disposed between the central element and the outer tubular element; wherein the at least one intermediate tubular element has a tapered distal end axially movable relative to the central element and the outer tubular element.
 37. The apparatus of claim 36, wherein the central element, the at least one intermediate tubular element, and the outer tubular element are mutually movable between a first operating configuration, at which the ogive-shaped distal end and the tapered distal ends form a substantially conical continuous surface, and a second operating configuration, at which a point of the ogive-shaped end and edges of the tapered distal ends lie in a same plane.
 38. The apparatus of claim 36, wherein keys are disposed between the central element, the at least one intermediate tubular element, and the outer tubular elements to prevent mutual rotation of the central element, the at least one intermediate tubular element, and the outer tubular element.
 39. The apparatus of claim 36, wherein the driving means comprises: at least one pair of first auxiliary motors; at least one pair of second auxiliary motors; and a pair of third auxiliary motors; wherein each first auxiliary motor is connected with an outer tubular element of a respective radially internal body, wherein each second auxiliary motor is connected to an intermediate tubular element of the respective radially internal body, and wherein each third auxiliary motor is connected to a central element of the respective radially internal body, wherein the first, second, and third auxiliary motors move the outer tubular element, the at least one intermediate tubular element, and the central element in a direction opposite to a moving forward direction of the respective radially external tubular body in the tubular covering sleeve, so as to first bring the ogive-shaped distal ends of the central elements into mutual contact, then bring the tapered distal ends of the outer tubular element, and the at least one intermediate tubular element into mutual contact, and finally bring distal ends of the radially external tubular bodies into mutual contact.
 40. The apparatus of claim 39, wherein each radially internal body, the respective first auxiliary motor, the respective second auxiliary motor, and the respective at least one third auxiliary motor are installed on a main support assembly that is movable between a disengaged position, at which the radially internal body lies spaced apart from the respective radially external tubular body, and an engaged position, at which the radially internal body is inserted in the respective radially external tubular body.
 41. The apparatus of claim 40, wherein the outer tubular element of the radially internal body is provided, on a proximal end thereof, with an outer thread engaged by a lead nut rotatably mounted on the main support assembly and connected to the respective first auxiliary motor.
 42. The apparatus of claim 41, wherein a belt drive connects the respective first auxiliary motor to a respective lead nut.
 43. The apparatus of claim 41, wherein the respective first auxiliary motor is fixed relative to the main support assembly.
 44. The apparatus of claim 39, wherein the at least one intermediate tubular element of the radially internal body is provided, on a proximal end thereof, with an outer thread engaged by a lead nut rotatably mounted on the outer tubular element and connected to the respective second auxiliary motor.
 45. The apparatus of claim 44, wherein a belt drive connects the respective second auxiliary motor to a respective lead nut.
 46. The apparatus of claim 44, wherein the respective second auxiliary motor is movable relative to the main support assembly together with the respective outer tubular element.
 47. The apparatus of claim 39, wherein the central element of the radially internal body is provided, on a proximal end thereof, with an outer thread engaged by a lead nut slidably mounted on a proximal end of the intermediate tubular element and connected to the respective third auxiliary motor.
 48. The apparatus of claim 47, wherein a belt drive connects the respective third auxiliary motor to a respective lead nut.
 49. The apparatus of claim 47, wherein the respective third auxiliary motor is movable relative to the main support assembly together with the respective intermediate tubular element. 